[llvm-branch-commits] [llvm] release/19.x: [RemoveDIs] Fix spliceDebugInfo splice-to-end edge case (#105671, #106723) (PR #106952)

[Orlando Cazalet-Hyams via llvm-branch-commits]

https://github.com/OCHyams commented:

Hi @tru,

> Is this PR a fix for a regression or a critical issue?

Neither

> What is the risk of accepting this into the release branch?

If I've made a mistake in the patch we could get incorrect debug-info in an edge case. I've added some comments inline that explain why this patch won't introduce any new null or `end()` derefs. If somehow those comments are all wrong, this change would only cause an issue for the same edge case that already runs into one (see below).

> What is the risk of NOT accepting this into the release branch?

There's a specific debug info circumstance edge case that results in an `end()` iterator dereference when this function is called. It took 6 months of usage for the edge case to materialise, so it's not common - the bug was reported in #105571.

Happy to provide more info if needed.

https://github.com/llvm/llvm-project/pull/106952